If the Tedd Cash lens cover is loose, just pinch it on the sides and it will work fine. Its brass, unless you bought one made of steel. Either can be pinched and will hold. Its just a friction fit over the lens mount.
I played around with larger lenses as a kid, when I didn't know what " dry " meant. I burned holes in lots of things trying to get a fire going. If you carry charred cloth, use it to begin an ember. Then put your charred cloth in your nest of dry tinder, and blow or wave it into a fire. Always have all your firemaking sticks ready by your hearth BEFORE you begin starting a fire. It goes very quickly, but dry tinder burns up quickly. As hard as it is to find and keep dry tinder, you don't want to waste any of it. If you are out of charred cloth, put some black powder on a cleaning patch( dry, turn an edge over and rub the patching between your fingers to crush the powder and rub it into the cloth. Then use that to begin an ember with your lens. The blackened area will absorb heat much better than the white. You can do the same with dry bark. If you don't have BP with you, you can find Birch bark which contains an oil. Some say that Sycamore and popular bark also seem to work well and have some kind of oils in them, but I have no experience with them. You can find dead cottonwood( poplar) trees in most of the U.S. with limbs well off the ground that are peeling bark. That is the bark to pick, not something off a limb lying on the ground and half buried by weeds. I have used dead poplar leaves- broad and flat and brown- to start a fire with a lens, and I did get an ember going. I did not know then how to blow that ember into a fire, but if you can get an ember, you can make fire.